Gallic acid

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Gallic acid
Gallic acid.svg
Ácido gálico.png
IUPAC name
3,4,5-Trihydroxybenzoic acid
Other names
Gallic acid
149-91-7 YesY
5995-86-8 (monohydrate) N
ChEBI CHEBI:30778 YesY
ChEMBL ChEMBL288114 YesY
ChemSpider 361 YesY
EC Number 205-749-9
Jmol interactive 3D Image
KEGG C01424 YesY
PubChem 370
RTECS number LW7525000
UNII 632XD903SP YesY
Molar mass 170.12 g/mol
Appearance White, yellowish-white, or
pale fawn-colored crystals.
Density 1.694 g/cm3 (anhydrous)
Melting point 260 °C (500 °F; 533 K)
1.19 g/100 mL, 20°C (anhydrous)
1.5 g/100 mL, 20 °C (monohydrate)
Solubility soluble in alcohol, ether, glycerol, acetone
negligible in benzene, chloroform, petroleum ether
log P 0.70
Acidity (pKa) COOH: 4.5, OH: 10.
Main hazards Irritant
Safety data sheet External MSDS
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity (yellow): no hazard code Special hazards (white): no codeNFPA 704 four-colored diamond
Lethal dose or concentration (LD, LC):
5000 mg/kg (rabbit, oral)
Related compounds
carboxylic acids
Related compounds
Benzoic acid, Phenol, Pyrogallol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Gallic acid is a trihydroxybenzoic acid, a type of phenolic acid, a type of organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants.[1] The chemical formula is C6H2(OH)3COOH. Gallic acid is found both free and as part of hydrolyzable tannins. The gallic acid groups are usually bonded to form dimers such as ellagic acid. Hydrolysable tannins break down on hydrolysis to give gallic acid and glucose or ellagic acid and glucose, known as gallotannins and ellagitannins respectively.[2]

Gallic acid forms intermolecular esters (depsides) such as digallic and trigallic acid, and cyclic ether-esters (depsidones).[3]

Gallic acid is commonly used in the pharmaceutical industry.[4] It is used as a standard for determining the phenol content of various analytes by the Folin-Ciocalteau assay; results are reported in gallic acid equivalents.[5] Gallic acid can also be used as a starting material in the synthesis of the psychedelic alkaloid mescaline.[6]

The name is derived from oak galls, which were historically used to prepare tannic acid. Despite the name, gallic acid does not contain gallium. Salts and esters of gallic acid are termed "gallates".

Historical context and uses[edit]

Gallic acid is an important component of iron gall ink, the standard European writing and drawing ink from the 12th to 19th century with a history extending to the Roman empire and the Dead Sea Scrolls. Pliny the Elder (23-79 AD) describes his experiments with it and writes that it was used to produce dyes. Galls (also known as oak apples) from oak trees were crushed and mixed with water, producing tannic acid. It could then be mixed with green vitriol (ferrous sulfate) — obtained by allowing sulfate-saturated water from a spring or mine drainage to evaporate — and gum arabic from acacia trees; this combination of ingredients produced the ink.[7]

Gallic acid was one of the substances used by Angelo Mai (1782–1854), among other early investigators of palimpsests, to clear the top layer of text off and reveal hidden manuscripts underneath. Mai was the first to employ it, but did so "with a heavy hand", often rendering manuscripts too damaged for subsequent study by other researchers.[citation needed]

Gallic acid was first studied by the Swedish chemist Carl Wilhelm Scheele in 1786.[8] In 1818 the French chemist and pharmacist Henri Braconnot (1780–1855) devised a simpler method of purifying gallic acid from galls;[9] gallic acid was also studied by the French chemist Théophile-Jules Pelouze (1807–1867),[10] among others.

George Washington used gallic acid to communicate with spies[clarification needed] during the American Revolutionary War, according to the miniseries America: The Story of Us.[citation needed]

Gallic acid is a component of some pyrotechnic whistle mixtures.



Chemical structure of 3,5-didehydroshikimate

Gallic acid is formed from 3-dehydroshikimate by the action of the enzyme shikimate dehydrogenase to produce 3,5-didehydroshikimate. This latter compound tautomerizes to form the redox equivalent gallic acid, where the equilibrium lies essentially entirely toward gallic acid because of the coincidentally occurring aromatization.[11][12]


Gallate dioxygenase is an enzyme found in Pseudomonas putida that catalyses the reaction

gallate + O2 → (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate.

Gallate decarboxylase is another enzyme in the degradation of gallic acid.


Gallate 1-beta-glucosyltransferase is an enzyme that uses UDP-glucose and gallate, whereas its two products are UDP and 1-galloyl-beta-D-glucose.

Natural occurrences[edit]

Gallic acid is found in a number of land plants, such as the parasitic plant, Cynomorium coccineum,[13] the aquatic plant, Myriophyllum spicatum, and the blue-green alga, Microcystis aeruginosa.[14]


Gallic acid is easily freed from gallotannins by acidic or alkaline hydrolysis. When gallic acid is heated with concentrated sulfuric acid, rufigallol is produced by condensation. Oxidation with arsenic acid, permanganate, persulfate, or iodine yields ellagic acid, as does reaction of methyl gallate with iron(III) chloride.[3]


List of plants that contain gallic acid[edit]

In food[edit]

Spectral data[edit]

Lambda-max: 220, 271 nm (ethanol)
Spectrum of gallic acid
Extinction coefficient (log ε)
Major absorption bands ν : 3491, 3377, 1703, 1617, 1539, 1453, 1254 cm−1 (KBr)
Proton NMR

d : doublet, dd : doublet of doublets,
m : multiplet, s : singlet

δ :

7.15 (2H, s, H-3 and H-7)

Carbon-13 NMR


δ :

167.39 (C-1),
144.94 (C-4 and C-6),
137.77 (C-5),
120.81 (C-2),
109.14 (C-3 and C-7)

Other NMR data
Masses of
main fragments
ESI-MS [M-H]- m/z : 169.0137 ms/ms (iontrap)@35 CE m/z product 125(100), 81(<1)



Also known as galloylated esters:

Health effects[edit]

It is a weak carbonic anhydrase inhibitor.[23] In basic research, gallic acid extracted from grape seeds has been shown to inhibit the formation of amyloid fibrils, one of the potential causes of Alzheimer's disease and Parkinson's disease.[24][25][26] One study indicated that gallic acid has this effect on amyloid protein formation by modifying the properties of alpha-synuclein, a protein associated with the onset of neurodegenerative diseases.[26]

Gallic acid is classified as mutagen and teratogen.[3]

Potential uses[edit]

It can be used to produce polyesters based on phloretic acid and gallic acid.[27]

See also[edit]


  1. ^ LD Reynolds and NG Wilson, "Scribes and Scholars" 3rd Ed. Oxford: 1991. pp193–4.
  2. ^ Andrew Pengelly (2004), The Constituents of Medicinal Plants (2nd ed.), Allen & Unwin, pp. 29–30 
  3. ^ a b c Edwin Ritzer; Rudolf Sundermann (2007), "Hydroxycarboxylic Acids, Aromatic", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), Wiley, p. 6 
  4. ^ Fiuza, S. M.; Gomes, C.; Teixeira, L. J.; Girão da Cruz, M. T.; Cordeiro, M. N. D. S.; Milhazes, N.; Borges, F.; Marques, M. P. M. "Phenolic acid derivatives with potential anticancer properties––a structure–activity relationship study. Part 1: Methyl, propyl and octyl esters of caffeic and gallic acids". Bioorganic & Medicinal Chemistry (Elsevier) 12 (13): 3581–3589. doi:10.1016/j.bmc.2004.04.026. 
  5. ^ Andrew Waterhouse. "Folin-Ciocalteau Micro Method for Total Phenol in Wine". UC Davis. 
  6. ^ Tsao, Makepeasce (July 1951). "A New Synthesis Of Mescaline". Journal of the American Chemical Society 73 (11): 5495–5496. doi:10.1021/ja01155a562. ISSN 0002-7863. 
  7. ^ Fruen, Lois. "Iron Gall Ink". 
  8. ^ Carl Wilhelm Scheele (1786) "Om Sal essentiale Gallarum eller Gallåple-salt" (On the essential salt of galls or gall-salt), Kongliga Vetenskaps Academiens nya Handlingar (Proceedings of the Royal [Swedish] Academy of Science), vol 7, pages 30-34.
  9. ^ Braconnot Henri (1818). "Observations sur la préparation et la purification de l'acide gallique, et sur l'existence d'un acide nouveau dans la noix de galle" [Observations on the preparation and purification of gallic acid, and on the existence of a new acid in galls]. Annales de chimie et de physique 9: 181–184. 
  10. ^ J. Pelouze (1833) "Mémoire sur le tannin et les acides gallique, pyrogallique, ellagique et métagallique," Annales de chimie et de physique, vol. 54, pages 337-365 [presented February 17, 1834].
  11. ^ Gallic acid pathway on
  12. ^ Dewick, PM; Haslam, E (1969). "Phenol biosynthesis in higher plants. Gallic acid". Biochemical Journal 113 (3): 537–542. PMC 1184696. PMID 5807212. 
  13. ^ Zucca, Paolo; Rosa, Antonella; Tuberoso, Carlo; Piras, Alessandra; Rinaldi, Andrea; Sanjust, Enrico; Dessì, Maria; Rescigno, Antonio (11 January 2013). "Evaluation of Antioxidant Potential of "Maltese Mushroom" (Cynomorium coccineum) by Means of Multiple Chemical and Biological Assays". Nutrients 5 (1): 149–161. doi:10.3390/nu5010149. PMC 3571642. PMID 23344249. 
  14. ^ Nakai, S (2000). "Myriophyllum spicatum-released allelopathic polyphenols inhibiting growth of blue-green algae Microcystis aeruginosa". Water Research 34 (11): 3026–3032. doi:10.1016/S0043-1354(00)00039-7. 
  15. ^ Mämmelä, Pirjo; Savolainen, Heikki; Lindroos, Lasse; Kangas, Juhani; Vartiainen, Terttu (2000). "Analysis of oak tannins by liquid chromatography-electrospray ionisation mass spectrometry". Journal of Chromatography A 891 (1): 75–83. doi:10.1016/S0021-9673(00)00624-5. PMID 10999626. 
  16. ^ a b Chanwitheesuk, Anchana; Teerawutgulrag, Aphiwat; Kilburn, Jeremy D.; Rakariyatham, Nuansri (2007). "Antimicrobial gallic acid from Caesalpinia mimosoides Lamk". Food Chemistry 100 (3): 1044–1048. doi:10.1016/j.foodchem.2005.11.008. 
  17. ^ Alemika, Taiwo E.; Onawunmi, Grace O.; Olugbade, Tiwalade A. (2007). "Antibacterial phenolics from Boswellia dalzielii". Nigerian Journal of Natural Products and Medicine 10 (1): 108–10. 
  18. ^ a b Pandurangan AK, Mohebali N, Norhaizan ME, Looi CY (2015). "Gallic acid attenuates dextran sulfate sodium-induced experimental colitis in BALB/c mice". Drug Design, Development and Therapy 9: 3923–34. doi:10.2147/DDDT.S86345. PMC 4524530. PMID 26251571. 
  19. ^ Hodgson JM, Morton LW, Puddey IB, Beilin LJ, Croft KD (2000). "Gallic acid metabolites are markers of black tea intake in humans". Journal of Agricultural and Food Chemistry 48 (6): 2276–80. doi:10.1021/jf000089s. PMID 10888536. 
  20. ^ Pathak, S. B.; Niranjan, K.; Padh, H.; Rajani, M.; et al. (2004). "TLC Densitometric Method for the Quantification of Eugenol and Gallic Acid in Clove". Chromatographia 60 (3–4): 241–244. doi:10.1365/s10337-004-0373-y. 
  21. ^ Gálvez, Miguel Carrero; Barroso, Carmelo García; Pérez-Bustamante, Juan Antonio (1994). "Analysis of polyphenolic compounds of different vinegar samples". Zeitschrift für Lebensmittel-Untersuchung und -Forschung 199: 29–31. doi:10.1007/BF01192948. 
  22. ^ Koyama, K; Goto-Yamamoto, N; Hashizume, K (2007). "Influence of maceration temperature in red wine vinification on extraction of phenolics from berry skins and seeds of grape (Vitis vinifera)". Bioscience, Biotechnology, and Biochemistry 71 (4): 958–65. doi:10.1271/bbb.60628. PMID 17420579. 
  23. ^ Satomi, H; Umemura, K; Ueno, A; Hatano, T; Okuda, T; Noro, T (1993). "Carbonic anhydrase inhibitors from the pericarps of Punica granatum L". Biological & Pharmaceutical Bulletin 16 (8): 787–90. doi:10.1248/bpb.16.787. PMID 8220326. 
  24. ^ Liu, Y; Pukala, T. L.; Musgrave, I. F.; Williams, D. M.; Dehle, F. C.; Carver, J. A. (2013). "Gallic acid is the major component of grape seed extract that inhibits amyloid fibril formation". Bioorganic & Medicinal Chemistry Letters 23 (23): 6336–40. doi:10.1016/j.bmcl.2013.09.071. PMID 24157371. 
  25. ^ Wang, Y. J.; Thomas, P; Zhong, J. H.; Bi, F. F.; Kosaraju, S; Pollard, A; Fenech, M; Zhou, X. F. (2009). "Consumption of grape seed extract prevents amyloid-beta deposition and attenuates inflammation in brain of an Alzheimer's disease mouse". Neurotoxicity Research 15 (1): 3–14. doi:10.1007/s12640-009-9000-x. PMID 19384583. 
  26. ^ a b Liu, Y; Carver, J. A.; Calabrese, A. N.; Pukala, T. L. (2014). "Gallic acid interacts with α-synuclein to prevent the structural collapse necessary for its aggregation". Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 1844 (9): 1481–1485. doi:10.1016/j.bbapap.2014.04.013. PMID 24769497. 
  27. ^ Reina, Antonio; Gerken, Andreas; Zemann, Uwe; Kricheldorf, Hans R. (1999). "New polymer syntheses, 101. Liquid-crystalline hyperbranched and potentially biodegradable polyesters based on phloretic acid and gallic acid". Macromolecular Chemistry and Physics 200 (7): 1784–1791. doi:10.1002/(SICI)1521-3935(19990701)200:7<1784::AID-MACP1784>3.0.CO;2-B. 

External links[edit]